Preheat the oven to 350 degrees F (175 degrees C). Grease two 12-cup muffin tins or line cups with paper liners.
Beat butter and sugar together in a large bowl with an electric mixer until light and fluffy. Add ½ of the flour and ½ of the eggs; beat until smooth. Add remaining flour and eggs and beat until batter is light and fluffy.
Spoon batter into the prepared muffin cups, filling each ¾ full.
Bake in the preheated oven until tops spring back when lightly pressed, about 10 to 12 minutes. Cool in the tins for 5 minutes. Transfer to a wire rack to cool completely.
